1. Field of the Invention
This invention relates to an apparatus for controlling a flow of fine particles which is utilized by transferring means or blowing means of fine particles and is expected to be useful for film forming working, formation of a composite material, and dope working with fine particles, and the new field for formation of fine particles.
In the present specification, fine particles refer to atoms, molecules, ultra-fine particles and usual fine particles. Here, ultra-fine particles refer to ultra-minute particles (generally 0.5 .mu.m or less) obtained by, for example, vaporization in gas plasma vaporization, a gas phase chemical reaction, the colloidal precipitation method, the solution spraying pyrolysis method, utilizing a liquid phase reaction, etc. The usual fine particles refers to minute particles obtained by the general methods such as mechanical pulverization, precipitating treatment, etc. A beam in the present specification refers to a jet stream flowing in a certain direction with directivity with a higher density than the surrounding space, regardless of its sectional. shape.
2. Related Background Art
Generally speaking, fine particles can be dispersed and suspendedin a carrier gas, and delivered through the flow of the carrier gas.
In the prior art, the flow control of fine particles for delivery of the above fine particles has been performed only by partitioning the whole pathway of the fine particles flowing together with the carrier gas through the pressure difference between the upstream side and the downstream side with a pipe or a casing. Accordingly, the flow of fine particles will necessarily spread independently of the flow velocity within a whole pipe or casing which partitions the pathway of fine particles.
Also, when fine particles are blown against a substrate, etc., it has been practiced to jet out fine particles together with a carrier gas through a nozzle. The nozzles used for blowing of fine particles are simple parallel pipes or a nozzle convergent toward its end tip, and surely the sectional area of the jet stream of the fine particles immediately after jetting is narrowed corresponding to the area of the end of the nozzle. However, since the jet stream is diffused at the outlet surface of the nozzle, it is no more than that obtained by narrowing temporarily the pathway, and the velocity of the jet stream will never surpass acoustic velocity.
Whereas, by partitioning the whole pathway of fine particles with a pipe or a casing and delivering fine particles together with a carrier gas along the pathway through the pressure difference between the upstream side and the downstream side, it is impossible to obtain a high delivering speed. Also, it is difficult to avoid contact between the wall surfaces of the pipe or the casing partitioning the pathway of fine particles with fine particles over the whole delivering section. For this reason, and particularly in transporting active fine particles to their capturing position, such a method has the disadvantage that activity is liable to be lost with the lapse of time or through contact with the wall surface of the pipe or the casing. Also, if the whole pathway of the fine particles is patitioned with pipe material or casing members, due to the generation of dead space in the flow, etc., the capturing percentage of the fine particles delivered may be lowered or utilization efficiency of the carrier gas for the delivery of fine particles may be lowered.
On the other hand, a set of parallel tubes or a nozzle converging toward the end tip of prior art devices will produce a diffused stream with a broad density distribution of fine particles in the jet stream after passing through. Therefore, therethrough the problem arises that uniform blowing control is difficult to achieve in the case of blowing fine particles against a substrate, etc. The control of the region of the uniform flowing is also difficult to achieve.